Fertilizer Spikes?

Among other plants, I grow fruit and nut trees in wine barrels - I'm restricted to container gardening. I use both commercial organic fertilizer and fish emulsion regularly but wonder if fertilizer spikes are just as good; or if they'd be a worthwhile supplement - certainly they'd be much less work for me.

Anyone use them and if so how well have they worked for you? Also, any particularly good brands to consider? I know that they can be pricey but if they're worth it, they'd be a big time saver.

I think making your own compost/compost tea and looking up some Korean Natural Farming IMO techniques would be best. Just me though, the idea of buying a product like that is iffy, prefer a more natural path.

Agree that natural is best; that's why I use organic fertilizer.

I'm aware of the usual industrially produced type from the major players; but if anyone knows of, or has used, a gentler organic type spike, do tell.

I apologize, I should have been more clear. I meant a more homemade or very local source of fertilizer. Something where you can see the whole process; making sure it's all natural. It's hard for me to trust products online or at the store. Again, just me.

Ever consider making some worm bins to make some worm casting tea? Even grass clippings or weeds left in a bucket of water for a week, then strained will produce a good alternative to regular watering.

I hope you find your answer.